Ya, the weight can cause problems in the legs but I've ran a 12.10 1.5 mile at 263 lbs in the police academy last Oct. , but that was on grass. Uneven grass at that. My ankles are shot from 14 yrs. of football, so grass has it's pros and cons. The treadmill is the safest but I like to be outside. I ride alot MT bike but I feel the run does more and is better for job training since our Chief deep sixed the bike patrol.

Some years back I was training for my first marathon (The Disney!) when I hurt my knee. It was kinda weird cause it only hurt while I was running and didn't happen till after I got around the 12 mile point.

Come to find out I did all the wrong things. Wrong shoes, bad surface, poor warmup, and stretching. Lucky for me I worked with a good P.T. who was also certified to train.